What IGF-1 LR3 Is
IGF-1 LR3 (Long R3 IGF-1) is a synthetic 83-amino-acid analog of insulin-like growth factor 1, engineered so that the research community can study IGF-1-receptor signalling over a much longer window than native IGF-1 allows. Two structural changes define it: an arginine substitution at position 3 and a 13-residue N-terminal extension. Together these sharply reduce its affinity for the IGF-binding proteins (IGFBPs) that normally sequester circulating IGF-1, which is why its reported half-life is measured in hours rather than the minutes reported for the native molecule. This guide reviews its structure and research context for Canadian laboratories — as a scientific reference only, not as guidance for human use.
For the single-molecule background, see the IGF-1 LR3 encyclopedia entry.
Why the "LR3" Modification Matters
Native IGF-1 is tightly regulated in the body: most of it is bound to IGFBPs, and unbound IGF-1 is cleared within minutes. The LR3 modifications are the whole point of the analog in a research setting:
- Reduced IGFBP binding. The Arg-3 substitution lowers affinity for the binding proteins, so more of the molecule remains free to interact with the IGF-1 receptor (IGF-1R) in a model system.
- Extended footprint. With less protein sequestration, the reported half-life extends to roughly 20–30 hours versus the ~10–15 minutes reported for native IGF-1 — a difference that makes the analog practical to study across a longer timeline.
- Downstream of the growth-hormone axis. IGF-1 sits downstream of growth-hormone signalling, which is why the literature often studies it alongside GHRH-analog and secretagogue research tools such as CJC-1295 and ipamorelin.
Structure and Pharmacology at a Glance
| Property | IGF-1 LR3 |
|---|---|
| Class | Long-acting IGF-1 receptor (IGF-1R) analog |
| Length | 83 amino acids |
| Key modifications | Arg-3 substitution + 13-aa N-terminal extension |
| Half-life | ~20–30 hours (vs ~10–15 min native IGF-1) |
| Position in the axis | Downstream of the growth-hormone axis |
The extended half-life and reduced IGFBP binding are the structural features most relevant to how the analog behaves in solution and across a study. Its 98%+ HPLC purity target is documented on the IGF-1 LR3 1mg product page.
Reported Research Context (Third-Party Only)
IGF-1-receptor signalling is one of the more heavily studied pathways in cell-proliferation and tissue-biology research, and IGF-1 LR3 appears in that preclinical literature specifically because its longer footprint makes IGF-1R engagement easier to observe in a model system. For a Canadian research buyer, the relevance of that literature is strictly as scientific context for why the analog is studied — it is not a statement that the compound is approved for, or should be used in, any human or veterinary application by the reader. IGF-1 LR3 sold as a research peptide is for in vitro and preclinical laboratory work only.
Handling: Reconstitution and Storage
IGF-1 LR3 ships lyophilized and must be reconstituted before laboratory use:
- Use quality bacteriostatic water as the diluent — solution integrity depends on diluent quality as much as peptide purity, as the bacteriostatic water guide explains.
- Follow the peptide reconstitution guide for concentration technique, and use the IGF-1 LR3 reconstitution calculator to work out mg/mL concentration and syringe-unit math for a reconstituted research solution.
- Store per the peptide storage guide — larger polypeptides like IGF-1 LR3 are sensitive to repeated freeze-thaw cycling, and lyophilized powder and reconstituted solution have distinct stability windows.
Verifying Purity Before You Rely on It
For an 83-residue analog, the batch Certificate of Analysis is what turns a labelled purity number into a measured one — mass-spec confirmation of identity matters especially for a longer sequence. Independent third-party HPLC and mass-spec results, not an in-house figure, are the standard to insist on; see /lab-reports for published batch documentation and the Canadian vendor-selection guide for the full due-diligence framework.
Buying IGF-1 LR3 for Research in Canada
Lux BioPure lists IGF-1 LR3 1mg for domestic Canadian research fulfillment, alongside the growth-axis research tools CJC-1295 DAC and the wider catalog. Browse the full shop for current in-stock inventory, and read the Canadian buyer's guide for sourcing context.
Frequently Asked Questions
What does the "LR3" in IGF-1 LR3 mean? LR3 stands for Long R3 — an arginine (R) substitution at position 3 plus a 13-amino-acid N-terminal extension. These modifications reduce the analog's binding to IGF-binding proteins, so more of the molecule stays free to engage the IGF-1 receptor in a model system.
How is IGF-1 LR3 different from native IGF-1? IGF-1 LR3 is engineered to bind IGF-binding proteins far less than native IGF-1 does. The practical result reported in the literature is a much longer half-life — roughly 20–30 hours versus around 10–15 minutes for the native molecule.
Where does IGF-1 LR3 sit relative to growth-hormone peptides? IGF-1 sits downstream of the growth-hormone axis, which is why the research literature often studies IGF-1 LR3 alongside GHRH-analog and secretagogue tools such as CJC-1295 and ipamorelin rather than as a substitute for them.
Is IGF-1 LR3 sold as a research peptide the same as an approved medicine? No. IGF-1 LR3 sold as a research peptide is supplied for in vitro and preclinical laboratory research use only and is not an approved medicine for the buyer. Any reported research context is scientific background only, not an indication for human or veterinary use.
Research Disclaimer
This guide reviews the structure and published research context of IGF-1 LR3 for in vitro and preclinical laboratory contexts only. IGF-1 LR3 is not approved for human or veterinary therapeutic use by the reader under Health Canada or any regulatory authority, and nothing in this article constitutes medical advice, dosing guidance, or a recommendation for administration to humans or animals.